You'll begin next to a floating crate. You don't need it yet. Instead, track
forward and around the corner, sneaking up the ramp that leads to a large
warehouse. Pick off the guards in the distance. Fall back and use the ramp
as cover if you draw their fire. Then head up and finish them off.

Head forward until you reach the second channel in the crates to the right.
Keep creeping right, rounding corners until you reach a guard facing away
from you. Kill him at close range, then turn around and look for an explosive
crate sticking out of the stack to the left.

Head forward, sticking to the right side of the stacks. Keep to the right
edge of the wall, moving cautiously. When you see a cat walk ahead and above,
line up a shot on one of the guards here. Then take out the next one. If
you miss, they will run to a lift and come down to your level.

Continue around the stacks of crates, eliminating dD guards. They hide in
every nook and cranny, so don't leave a single inch of the ground floor
unexplored. When all the guards are dead, head upstairs on the lift.

Hidden Item:
Phoenix: This item is pretty difficult to get. From the elevator, head right.
Shoot the door behind the guard stationed in front of it. About 20% of the
time, doing this causes him to open the door and head through. Follow behind
him, moving up the ramp in the subsequent room to an elevator. Take the lift
up, then go down the hall through a couple groups of sliding doors. After
the last one, you'll find yourself in a cavernous room overlooking the hangar.
Grab the Phoenix from the bench.

Head past the elevator across the catwalk to a set of sliding doors. Open
them and head forward, keeping an eye overhead. In this huge, rocky chamber
are a series of catwalks overhead. Haul out the Dragon and drop the guards
as they run around to the lift.

Stay
where you are. The guards, once they see you, will seek you out. Fall back
a ways into the prior passage and wait. Often, sensing you nearby, the guards
will attempt to throw a grenade, accidentally killing themselves.

Once they've all been killed, return downstairs and grab that floating crate
near the beginning of the level. Bring it into the cavern and ride the next
lift up. Follow the catwalk around the wall until you reach a small X chiseled
into a silver strip of wall. Leave the crate here, then back up and shoot
it. This will open a passage into the next area.

Several guards will likely approach through the opening you've created. Fall
back and take them down as they step through, then head into the lab hall.

Perfect objective:
Destroy computer records

Go to the right, taking down the guards past each set of sliding doors. Follow
the path as it turns right. Now go to the silver door halfway down the hall
to the left. Enter and punch out the guard here. Equip the Data Uplink on
the computer terminal to download a virus, causing a gun across the hall
to shut down. Head to the silver door opposite and enter.

Punch out these labbies too, and again use the Uplink to download a virus.
This one makes the doors in this corridor malfunction. Head to the top of
the corridor and enter the door at the top to the right. Shoot the two guards
here, then shoot the lone computer terminal here. This will complete the
objective.

Exit
this room and head into the door to the right. Here you'll discover a Shield.
Leave this room and head to the right, down the long med hallway. At the
end of this corridor are a pair of facing doors. Step to the window of each
and eliminate the technicians that may be lurking here. Proceed through each
containment area.

Both contain dD guards, as well as tranquilizer-strapped lab techs. Use the
Dragon to quickly clear each room. When there's a break in the action, move
around the room pushing the green buttons. This will raise the containment
units. When this is done, you'll likely have company again. Guards come in
every couple of seconds. Just keep returning to the entrance to shoot the
intruders.

When all of the containment units have been raised, strap on the X-Ray vision.
You are looking for evidence in the form of alien bodies. Move around the
room, eyes trained on the central array. When you see the pale outline of
an alien form, look at it for a few moments. When you have successfully
determined it is an alien body, the objective will be complete.

2.
Obtain and use lab technician disguise

Return to the other leg of hallway, following it down until you see a set
of smaller silver doors across from each other. These doors are separate
entrances into a single locker room. You may encounter a guard on each side
of the locker room. Kill him, then find the shower room. Here (on Special
Agent), you'll discover a lab tech. Shoot him and grab the clothes he drops.
If playing Perfect, scour the lockers for the disguise.

Put it on immediately. You'll have 2:15 to find the first lab and enter.
When you don the clothes, the objective will be complete.

3. Gain access to autopsy lab

Go back to the hallway where you entered. On the right wall past the hole
you made to get in is a silver door. With the disguise on (and unarmed),
head to the back of the lab. Here, a guard at the door will let you pass.

Go to the right corner of the room and head through the door. When you enter,
you'll be found out. Kill anyone who gives you trouble, then open the door
to the glassed-in room. Grab the Med Lab Key Card. Objective 3 complete.

4.
Rescue the crash survivor

Leave this room and head right to another lab door. Equip your Dragon and
go in. There are several guards lurking behind partitions here. Peek to trigger
them, then fall back and shoot them as they move into the center of the room.

Go through the next door and eliminate all of the guards here. One of them
will drop yet another Key Card. Snag it and head to the door next to the
glassed experiment room. If you take too long to get there, the labbies will
destroy the alien on the gurney. The moment you step through the door to
the autopsy chamber, you will complete the mission.